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Query: UMLS:C1522282 (EMT)
 2,868 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of a range of different analogs of nicotinamide and benzamide on the X ray response of the EMT-6 tumor in vivo was investigated. Using an in vivo/in vitro survival assay, sensitization was seen at a dose of 2 mmole/kg for all but one of the analogs tested. The enhancement ratios (ER's) ranged from 1.0 to 1.5. Of particular interest were nicotinamide and SR-4350 which gave large ER's (1.5 and 1.4 respectively) at doses which were only about 12% of the LD50 values. In one normal tissue studied (skin reaction) a large single dose of nicotinamide (8 mmole/kg) only gave an ER of 1.1. These results will be discussed with reference to the mechanisms involved and the clinical implications.
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PMID:Preferential tumor radiosensitization by analogs of nicotinamide and benzamide. 294 59

Previous studies have implicated ADP-ribosylation in the mechanism of TNF cytotoxicity. In short-term 51Cr-release assays with several mouse and human tumor cell lines, the inhibitors aminobenzamide (ABA) and nicotinamide (NA) of ADP-ribosylation sensitized HER-2/neu-nonoverexpressing cells (CaOV-3 and MCF-7) but not HER-2/neu-overexpressing cells (SKOV-3 and SKBR-3) to TNF. However, both inhibitors alone or in combination with either TNF and/or actinomycin D (AD) caused similar effects on ADP-ribosylation rates of CaOV-3 and SKOV-3 cells after 4 h of treatment. This result suggests that ADP-ribosylation may not be involved in sensitizing these human tumor cells to TNF. Both ABA and NA decreased the TNF sensitivity of L929 cells and either increased or decreased TNF sensitivity of EMT-6 cells in the absence or presence of actinomycin D, respectively. Again, there was no correlation between ADP-ribosylation and TNF cytotoxicity in these mouse cell lines. Thus, modulation of TNF sensitivity by these inhibitors might be linked to a compromised repair mechanism distinct from the effects on ADP-ribosylation alone.
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PMID:TNF cytotoxicity: effects of HER-2/neu expression and inhibitors of ADP-ribosylation. 791 50

Rodent tumour models have been the 'workhorse' for tumour oxygenation research and for investigating radiobiological hypoxic fraction. Because of the intertumour heterogeneity of blood flow and related parameters, most studies have pooled information derived from several different tumours to establish the statistical significance of specific measurements. But it is the oxygenation status of and its modulation in individual tumours that has important prognostic significance. In that regard, the bioreducible hypoxic marker technique was tested for its potential to quantify oxygenation changes within individual tumours. Beta-D-iodinated azomycin galactoside (IAZG) and beta-D-iodinated azomycin xylopyranoside (IAZXP) were each radiolabelled with Iodine-125 and iodine-131 for measurements of animal tumour oxygenation. The tumour-blood (T/B) ratio of marker radioactivity in mice after the renal excretion of unbound marker (at 3 h and longer times) had been shown to be proportional to radiobiological hypoxic fraction. When markers labelled with both radioisotopes were administered simultaneously to EMT-6 tumour-bearing scid mice, T/B ratios were found to vary by up to 300% between different tumours, with an average intratumour variation of only approximately 4%. When the markers were administered 2.5-3.0 h apart, changes in T/B ratios of 8-25% were observed in 10 out of 28 (36%) tumours. Changes to both higher and lower hypoxic fraction were observed, suggestive of acute or cycling hypoxia. When 0.8 mg g(-1) nicotinamide plus carbogen was administered to increase tumour oxygenation, reductions in T/B ratios (mean deltaT/B approximately 38%) were observed in all tumours. Similar results were obtained with Dunning rat prostate carcinomas growing in Fischer x Copenhagen rats whose T/B ratios of IAZG and radiobiological hypoxic fractions are significantly lower. These studies suggest that fluctuating hypoxia can account for at least 25% of the total hypoxic fraction in some tumours and that correlations between bioreducible marker avidity and related tumour properties will be optimal when the independent assays are performed over the same time period. This dual hypoxic marker technique should prove useful for investigating both spontaneous and induced oxygenation changes within individual rodent tumours.
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PMID:A dual hypoxic marker technique for measuring oxygenation change within individual tumors. 968 88